The invention relates to a process for the selective production of phenyl-alkane and phenyl-alkane sulfonate compositions, to the particular phenyl-alkane are phenyl-alkane sulfonate compositions produced therefrom, and to uses of those compositions.
More than thirty years ago, many household laundry detergents were made of branched alkylbenzene sulfonates (BABS). BABS are manufactured from a type of alkylbenzenes called branched alkylbenzenes (BAB). Alkylbenzenes (phenyl-alkanes) refers to a general category of compounds having an aliphatic alkyl group bound to a phenyl group and having the general formula of (mi-alkyli)i-n-phenyl-alkane. The aliphatic alkyl group consists of an aliphatic alkyl chain, which is referred to by xe2x80x9calkanexe2x80x9d in the (mi-alkyli)i-n-phenyl-alkane formula. Of the chains of the aliphatic alkyl group, the aliphatic alkyl chain is the longest straight chain that has a carbon bound to the phenyl group. The aliphatic alkyl group may also consist of one or more alkyl group branches, each of which is attached to the aliphatic alkyl chain and is designated by a corresponding xe2x80x9c(mi-alkyli)ixe2x80x9d in the (mi-alkyli)i-n-phenyl-alkane formula. If it is possible to select two or more chains of equal lengths as the aliphatic alkyl chain, the choice goes to the chain carrying the greatest number of alkyl group branches. The subscript counter xe2x80x9cixe2x80x9d thus has a value of from 1 to the number of alkyl group branches, and for each value of i, the corresponding alkyl group branch is attached to carbon number mi of the aliphatic alkyl chain. The phenyl group is attached to the aliphatic alkyl group, specifically to carbon number n of the aliphatic alkyl chain. The aliphatic alkylation chain is numbered from one end to the other, the direction being chosen so as to give the lowest number possible to the position of the phenyl group.
The standard process used by the petrochemical industry for producing BAB consists of oligomerizing light olefins, particularly propylene, to branched olefins having 10 to 14 carbon atoms and then alkylating benzene with the branched olefins in the presence of a catalyst such as HF. Although the product BAB comprises a large number of alkyl-phenyl-alkanes having the general formula (mi-alkyli)i-n-phenyl-alkane, two examples of BAB are m-alkyl-m-alkyl-n-phenyl-alkanes where mxe2x89xa0n, and m-alkyl-m-phenyl-alkanes where mxe2x89xa72.
The most prominent common characteristic of BAB is that, for a large proportion of BAB, there is attached to the aliphatic alkyl chain of BAB generally at least one alkyl group branch, and more commonly three or more alkyl group branches. BAB thus has a relatively large number of primary carbon atoms per aliphatic alkyl group, since the number of primary carbon atoms per aliphatic alkyl group in BAB equals the number of alkyl group branches per aliphatic alkyl group plus either one if n=1, or two if nxe2x89xa72, provided that the alkyl group branches themselves are unbranched. If any alkyl group branch itself is branched, then the aliphatic alkyl group in BAB has even more primary carbon atoms. Thus the aliphatic alkyl group in BAB usually has three, four, or more primary carbon atoms. As for the alkyl group branches of the aliphatic alkyl group in BAB, each alkyl group branch is usually a methyl group branch, although ethyl, propyl, or higher alkyl group branches are possible.
Another typical characteristic of BAB is that the phenyl group in BAB can be attached to any non-primary carbon atom of the aliphatic alkyl chain. Except for 1-phenyl-alkanes whose formation is known to be disfavored due to the relative instability of the primary carbenium ion and neglecting the relatively minor effect of the branches of the branched paraffins, the oligomerization step produces a carbon-carbon double bond that is randomly distributed along the length of the aliphatic alkyl chain, and the alkylation step nearly randomly attaches the phenyl group to a carbon along the aliphatic alkyl chain. Thus, for example, a BAB that has an aliphatic alkyl chain having 10 carbon atoms would be expected to be an approximately random distribution of 2-, 3-, 4-, and 5-phenyl-alkanes, and the selectivity to 2-phenyl alkane would be 25 if the distribution was perfectly random, but is typically between about 10 and about 40.
A third common characteristic of BAB is that one of the carbons of the aliphatic alkyl group is a quaternary carbon. The quaternary carbon may, or may not, be the carbon in the aliphatic alkyl group that is bonded by a carbon-carbon bond to a carbon in the phenyl group. When a carbon atom on the alkyl side chain not only is attached to two other carbons on the alkyl side chain and to a carbon atom of an alkyl group branch but also is attached to a carbon atom of the phenyl group, the resulting alkyl-phenyl-alkane is referred to as a xe2x80x9cquaternary alkyl-phenyl-alkanexe2x80x9d or simply a xe2x80x9cquat.xe2x80x9d Thus, quats comprise alkyl-phenyl-alkanes having the general formula m-alkyl-m-phenyl-alkane. If the quaternary carbon is the second carbon atom numbered from an end of the alkyl side chain, the resulting 2-alkyl-2-phenyl-alkane is referred to as an xe2x80x9cend quat.xe2x80x9d If the quaternary carbon is any other carbon atom of the alkyl side chain, as in the second BAB example, then the resulting alkyl-phenyl-alkane is referred to as an xe2x80x9cinternal quat.xe2x80x9d In known processes for producing BAB, a relatively high proportion, typically greater than 10 mol-%, of the BAB is internal quats.
About thirty years ago it became apparent that household laundry detergents made of BABS were gradually polluting rivers and lakes. Investigation into the problem led to the recognition that BABS were slow to biodegrade. Solution of the problem led to the manufacture of detergents made of linear alkylbenzene sulfonates (LABS), which were found to biodegrade more rapidly than BABS. Today, detergents made of LABS are manufactured worldwide. LABS are manufactured from another type of alkylbenzenes called linear alkylbenzenes (LAB). The standard process used by the petrochemical industry for producing LAB consists of dehydrogenating linear paraffins to linear olefins and then alkylating benzene with the linear olefins in the presence of a catalyst such as HF or a solid catalyst. LAB are phenyl-alkanes comprising a linear aliphatic alkyl group and a phenyl group and have the general formula n-phenyl-alkane. LAB has no alkyl group branches, and consequently the linear aliphatic alkyl group normally has two primary carbon atoms (i.e., nxe2x89xa72). Another characteristic of LAB that is produced by the standard LAB process is that the phenyl group in LAB is usually attached to any secondary carbon atom of the linear aliphatic alkyl group. In LAB produced using HF catalyst the phenyl group is slightly more likely to attach to a secondary carbon near the center as opposed to near the end of the linear aliphatic alkyl group, while in LAB produced by the Detal(trademark) process approximately 25-35 mol-% of n-phenyl-alkanes are 2-phenyl-alkanes.
Over the last few years, other research has identified certain modified alkylbenzene sulfonates, which are referred to herein as MABS, which are different in composition from all alkylbenzene sulfonates used currently in commerce, including BABS and LABS, and from all alkylbenzene sulfonates produced by prior alkylbenzene processes, including those which alkylate aromatics using catalysts such as HF, aluminum chloride, silica-alumina, fluorided silica-alumina, zeolites, and fluorided zeolites. MABS also differ from these other alkylbenzene sulfonates by having improved laundry cleaning performance, hard surface cleaning performance, and excellent efficiency in hard and/or cold water, while also having biodegradability comparable to that of LABS.
MABS can be produced by sulfonating a third type of alkylbenzenes called modified alkylbenzenes (MAB), and the desired characteristics of MAB are determined by the desired solubility, surfactancy, and biodegradability properties of MABS. MAB comprises a large number of phenyl-alkanes, some of which may be phenyl-alkanes that are found in LAB and some of which may be phenyl-alkanes that are found in BAB, but the phenyl-alkanes that are found in BAB are not desirable phenyl-alkanes for MAB. The phenyl-alkanes in MAB are phenyl-alkanes comprising a lightly branched aliphatic alkyl group and a phenyl group and has the general formula (mi-alkyli)i-n-phenyl-alkane. Phenyl-alkanes in MAB usually have only one alkyl group branch, and the alkyl group branch is a methyl group, which is preferred, an ethyl group, or an n-propyl group, so that, where there is only one alkyl group branch and nxe2x89xa01, the aliphatic alkyl group in MAB has three primary carbons. A preferred MAB phenyl-alkane is a monomethyl-phenyl-alkane. However, the aliphatic alkyl group in a MAB phenyl-alkane may have two primary carbon atoms if there is only one alkyl group branch and n=1, or, if there are two alkyl group branches and nxe2x89xa01, four primary carbons. Thus, the first characteristic of MAB is that the average number of primary carbons in the aliphatic alkyl groups of the phenyl-alkanes in MAB is intermediate between that in BAB and that in LAB. Another characteristic of MAB is that it contains a high proportion of 2-phenyl-alkanes, namely that from about 40 to about 100% of phenyl groups are attached selectively to the second carbon atom as numbered from an end of the alkyl side chain.
A final characteristic of the MAB alkylate is that the MAB has a relatively low proportion of internal quats. Some internal quats such as 5-methyl-5-phenyl-undecane produce MABS that has shown slower biodegradation, but end quats such as 2-methyl-2-phenyl-undecane produce MABS that show biodegradation similar to that of LABS. For example, biodegradation experiments show that in a porous pot activated sludge treatment, the ultimate biodegradation was greater for sodium 2-methyl-2-undecyl[C14]benzenesulfonate than for sodium 5-methyl-5-undecyl[C14]benzenesulfonate. See the article entitled xe2x80x9cBiodegradation of Coproducts of Commercial Linear Alkylbenzene Sulfonate,xe2x80x9d by A. M. Nielsen et al., in Environmental Science and Technology, Vol. 31, No. 12, 3397-3404 (1997). A relatively low proportion, typically less than 10 mol-%, of MAB is internal quats.
Because of the advantages of MABS over other alkylbenzene sulfonates, catalysts and processes are sought that produce MAB with a selectivity to 2-phenyl-alkanes and selectivity away from internal quaternary phenyl-alkanes.
In one aspect, this invention is a process for the production of phenyl-alkanes, in particular modified alkylbenzenes (MAB), by adsorptive separation, dehydrogenation, and alkylation. The process is characterized by the composition of the adsorbent and desorbent pair used in the process. The adsorbent used is silicalite and the preferred desorbent comprises a C5-C8 linear paraffin, a C5-C8 cycloparaffin, and/or a branched paraffin such as isooctane.
A broad embodiment of this invention may be characterized as a process for producing phenyl-alkanes. A paraffinic feed stream comprising a C8-C28 acyclic paraffin having 2 or 3 primary carbon atoms and at least one other acyclic paraffin pass to an adsorption zone. The feed stream has a first concentration of the acyclic paraffin having 2 or 3 primary carbon atoms. The adsorption zone comprises a bed of an adsorbent comprising silicalite at adsorption promoting conditions to selectively adsorb the acyclic paraffin having 2 or 3 primary carbon atoms. A desorbent stream comprising at least one component selected from the group consisting of a C5-C8 cycloparaffin, a C5-C8 normal paraffin, and a C5-C8 branched paraffin contacts the bed of adsorbent. An adsorption extract having a second concentration of the acyclic hydrocarbon having 2 or 3 primary carbon atoms is recovered from the adsorption zone. The second concentration is greater than the first concentration. At least a portion of the adsorption extract passes to a dehydrogenation zone, which is operated at dehydrogenation conditions sufficient to dehydrogenate the acyclic paraffin having 2 or 3 primary carbon atoms. A dehydrogenated product stream comprising a C8-C28 acyclic monoolefin having 2 or 3 primary carbon atoms is recovered from the dehydrogenation zone. An aromatic feedstock comprising a phenyl compound and at least a portion of the dehydrogenated product stream comprising the acyclic monoolefin pass to an alkylation zone. The alkylation zone operates at alkylation conditions sufficient to alkylate the phenyl compound with the acyclic monoolefin in the presence of an alkylation catalyst to form a phenyl-alkane comprising a molecule having one phenyl portion and one C8-C28 aliphatic alkyl portion. The aliphatic alkyl portion has 2 or 3 primary carbon atoms and no quaternary carbon atoms except for any quaternary carbon atom bonded by a carbon-carbon bond with a carbon atom of the phenyl portion. The alkylation has a selectivity to 2-phenyl-alkanes of from 40 to 100 and a selectivity to internal quaternary phenyl-alkanes of less than 10. The phenyl-alkane is recovered from the alkylation zone. In a preferred embodiment, the alkylation has a selectivity to phenyl-alkanes having an aliphatic alkyl portion containing a quaternary carbon atom not bonded by a carbon-carbon bond with a carbon atom of the phenyl portion of less than 10, and more preferably less than 1.
This invention, when used for detergent alkylation, produces detergents that meet the increasingly stringent requirements of 2-phenyl-alkane selectivity and internal quaternary phenyl-alkane selectivity for the production of modified alkylbenzenes (MAB). Thus, in another process aspect of this invention, the MAB, in turn, can be sulfonated to produce modified linear alkylbenzene sulfonates (MABS), which have improved cleaning effectiveness in hard and/or cold water while also having biodegradability comparable to that of linear alkylbenzene sulfonates.
In yet other aspect, this invention is the MAB and MABS compositions produced by the processes of this invention. The processes of this invention produce particular MAB and MABS products having aliphatic alkyl chains with specially tailored extents of branching that are not necessarily the same as those of the prior art processes.
This invention is, in another of its aspects, the use of MAB and MABS produced by the process of this invention as a lubricant and as a lubricant additive, respectively.
Additional aspects and embodiments are described in the following description of this invention.
LAB processes are described in the book edited by Robert A. Meyers entitled Handbook of Petroleum Refining Processes, (McGraw-Hill, New York, Second Edition, 1997) at pages 1.53 to 1.66, the teachings of which are incorporated herein by reference. Paraffin dehydrogenation processes are described in the Meyers book at pages 5.11 to 5.19, the teachings of which are incorporated herein by reference.
PCT International Publication Nos. WO 99/05082, WO 99/05084, 99/05241, and WO 99/05243, all four of which were published on Feb. 4, 1999, and which are incorporated herein by reference, disclose alkylation processes for uniquely lightly branched or delinearized alkylbenzenes. PCT International Publication No. W099/07656, published on Feb. 18, 1999, which is incorporated herein by reference, discloses processes for such alkylbenzenes using adsorptive separation.
U.S. Pat. No. 5,276,231 (Kocal et al.) describes a process for the production of linear alkylaromatics with selective removal of aromatic by-products of the paraffin dehydrogenation zone of the process. In U.S. Pat. No. 5,276,231, paraffins from the paraffin column of the alkylation zone are recycled to the reactor of the dehydrogenation zone, with or without selective hydrogenation of any monoolefins in the paraffin recycle stream. U.S. Pat. No. 5,276,231 also teaches the selective hydrogenation of diolefinic by-products from the dehydrogenation zone. The teachings of U.S. Pat. No. 5,276,231 are incorporated herein by reference.
U.S. Pat. Nos. 5,196,574 (Kocal) and U.S. Pat. No. 5,344,997 (Kocal) describe alkylation of aromatics using a fluorided silica-alumina catalyst. U.S. Pat. No. 5,302,732 (Steigleder et al.) describes alkylation of aromatics using an ultra-low sodium silica-alumina catalyst. The teachings of U.S. Pat. Nos. 5,196,574, 5,302,732, and 5,344,997 are incorporated herein by reference.